1. Field
This disclosure relates to real-time transmission over data networks, more particularly to methods and devices used to improve quality of service for real-time transmission over data networks.
2. Background
As more sophisticated equipment has become available, transmission of data from real-time sources such as voice and video has become more prevalent. Data networks are often designed to accommodate the maximum bandwidth required. However, the network traffic may ‘burst’ up to that capacity, but more often runs at a lower rate. This provides excess capacity in data networks to transmit such things as video and voice. Enterprises, such as companies and government entities, have found the use of data networks for voice transmission, especially, to be a cost-effective alternative to using the public switched transmission network (PSTN).
However, the use of data networks for real-time transmissions such as voice and voice raises concerns about the quality of service (QoS). Network access providers typically offer a range of service levels to enterprises for corresponding fees. The network may be ‘purchased’ by the enterprise as a virtual circuit, which is a logical circuit created to ensure reliable communication between network devices.
One concern about QoS is congestion on the network. Even though the network may have excess capacity at some times, at other time it may be ‘full’ and there may be delays in transmission. If the transmissions are data packets or modules, there is generally not a problem except the sender and receiver's inconvenience. However, if the transmissions are real-time data packets or modules, the delay may be fatal to the overall transmission, since the packets or modules have to arrive with enough time to be decoded into a sequential data stream. Delayed packets or modules will cause the sequential order to be disrupted and will adversely affect the reception of the real-time transmission.
A possible solution is to have a VC dedicated to voice. However, this would typically require an enterprise or user to have two VCs, one dedicated to voice and one for data. Even if the enterprise or user only used one VC, the costs would be greater. It would be preferable for the voice and data traffic to share a VC but without sacrificing quality of service for the voice, and still have a reasonable cost.